THE SWEET LIFE: Bill and Sarabeth Levine found the recipe for happiness and success in their prewar four-bedroom apartment.Photos by Lorenzo Ciniglio

Bill and Sarabeth Levine (Lorenzo Ciniglio)

They purchased the full-floor residence for just $135,000 when the former rental building was converted to co-ops 30 years ago.

Her mother’s desk

A jar of marmalade, because that was how they started their business

Bill and Sarabeth Levine — owners of the famed Sarabeth’s restaurants, along with a bakery and jam factory — are positive that their Upper West Side apartment brought them luck.

Bill, now 81, lived there first, renting it for $385 a month in 1975.

Sarabeth, 70, was a divorced mother of two living on Long Island and selling insurance for a living when she persuaded an aunt to share the super-secret family recipe for marmalade with her. (The recipe was always — and still remains — a tightly held secret.)

The couple met in 1980. “I was building a cafe then,” Bill says, “and she said she had a great recipe for orange marmalade that she wanted to sell in my cafe.”

They quickly fell in love, got engaged and moved in together. And Sarabeth, who continued selling insurance by day, started hurrying home each night to make marmalade. “We served it in the cafe, and everybody wanted to know where they could buy it,” Bill says.

The two married in 1981 and opened a small store on Amsterdam Avenue to sell the marmalade.

“Who would dream of having a jam shop up there?” Bill recalls. “At that time, 79th Street was like the DMZ, and the store was on 80th Street — the wrong side of the zone.”

“I still remember people looking in the window and betting we’d never make it,” Sarabeth says.

But she refused to let it fail. “I went to Balducci’s and told them Bloomingdale’s bought it — which wasn’t true,” she says. “Then I went to Bloomingdale’s and told them Balducci’s had it. And that’s how I went into business.”

They eventually moved their store into a bigger space across Amsterdam Avenue in 1986; it now houses one of their 11 restaurants (the most recent one opened on Park Avenue South in February). They also have a bakery in Chelsea Market, and a factory where they produce a million jars of spreadable fruit a year.

“That’s why we say it’s a lucky apartment,” Sarabeth says.

Besides being lucky, the apartment, in a 1910 building, is also large. They have an entire floor — 1,500 square feet, with four bedrooms, two bathrooms, a living/dining room and an eat-in kitchen. The building was converted to co-ops in 1983, and they bought the apartment at the insider’s price — $135,000.

“We did a lot of renovations,” Bill says. “We put in molding, we finished the floors, we made a little dressing-room area, put in arched doorways and mirrored French doors, and we also created a small meditation area for Sarabeth.”

There was also a red brick wall and matching working fireplace. “Sarabeth didn’t like that,” Bill says, “so she painted it all white herself.”

She also brought in some of the apartment’s nicest furnishings. “I’m walking down the street one day,” Sarabeth says, “and I see these two red chairs sitting in the street right outside my building. We’re Mr. and Mrs. Dumpster Diver. So it’s not strange for me to come upstairs with something I found in the street. I bring in these chairs. What do I know from what it says on the back?”

What she didn’t realize at the time was that the label on the back said they were very posh Maison Gatti bistro chairs. Some time later, they bought a kitchen table and decided they needed four more chairs.

“I found a store downtown that had the chairs,” Sarabeth continues. “The saleswoman said they can take the order, but it would be an over-three-month wait while they sent it over in a container from Paris. So now I knew that these were not just any old chairs. Then we got to the price. They were $1,200 or $1,300 apiece.

“The next weekend, I’m driving down Columbus Avenue past a Housing Works store. I look in the window, and they have these chairs. So I stop the car, jump out and go inside, and they’re having an online auction. I check the back of the chairs, and they have the Maison Gatti label. So I bid on them and prayed that no one else got them. And I wound up with six of these extraordinary chairs for $900!”

Sarabeth also bought a piano so big that it could only come into the apartment after a window was removed. She also purchased a hand-painted table from the 1930s with a silver design on the underside of the glass, and several pieces of artwork by friend/artist Tina Salvesen.

“Our home isn’t about style,” she says. “It’s about feelings. It’s having things around that we love and make us feel good. And we’re so happy here.”